Boundary critical phenomena in SU(3) 'spin' chains

ySU(3)-invariant 'spin' chains with a single impurity, such as a modified exchange coupling on one link, are analysed using boundary conformal field theory techniques, These chains are equivalent to a special case of the 'tJV' model, i.e, the tJ model with a nearest-neighbour repulsion added. In the continuum limit they are equivalent to two free bosons at a special value of the compactification radii, The SU(3) symmetry, which is made explicit in this formulation, provides insight into the exact solution of a non-trivial boundary critical point found earlier in another formulation of this model as a theory of quantum Brownian motion.